The invention relates to a high-pressure pump for fuel delivery in fuel injection systems of internal combustion engines, particularly in a common rail injection system which includes a tank, a pre-feed pump, and the high-pressure pump. The pre-feed pump aspirates a total fuel flow from the tank and this total fuel flow is divided into a lubricating flow, which is conveyed through the high-pressure pump for the purpose of lubrication, and a delivery flow, which is acted on with high pressure by the high-pressure pump and delivered to a common distributor rail.
Up till now, the proposal has been made to execute the division into a lubricating flow and a delivery flow upstream of the inlet of the high-pressure pump downstream of the pre-feed pump. The lubricating flow is then conveyed separately through the pump housing of the high-pressure pump. The delivery flow can be metered as needed and supplied to the high-pressure pump. The metering of the injection quantity can be carried out by a speed-regulated, electrical pre-feed pump. Another proposal provides for a mechanical pre-feed pump whose motor speed-dependent delivery flow is divided by means of an overflow valve into a lubricating flow and a delivery flow to the high-pressure elements of the high-pressure pump. The metering of the elements of the high-pressure pump then takes place by means of a magnet-controlled valve. The fuel quantity supplied to the individual elements of the high-pressure pump can therefore be varied. However, in the system that has been proposed up till now, damages have occurred, whose causes can be traced to an insufficient lubricating flow, in particular when starting using a mechanical pre-feed pump. It has furthermore turned out to be disadvantageous that the embodiments proposed previously require a large number of separate parts, which drives up manufacturing costs.